Monitoring direct and indirect transmission of infections in a healthcare facility using a real-time locating system

ABSTRACT

An infectious disease transmission tracking system ( 10 ) includes a real-time locating system (RTLS) ( 12 ) configured to track locations of tags ( 14, 15 ) in a monitored area. At least one electronic processor ( 22 ) is in operative communication with the RTLS to receive locations of tags in the monitored area. A non-transitory storage medium stores, a map ( 30 ) of the monitored area; a nodes database ( 32 ) storing information on nodes ( 18 ) in which each node is a person, a mobile object, or a map zone and the nodes database stores information on the nodes including at least (i) an identification of each node as a person, a mobile object, or a map zone, (ii) an identification of a tag associated with each node that is identified as a person or a mobile object, (iii) locational information on the map for each node that is identified as a map zone, and (iv) an infection likelihood for each node with respect to a tracked pathogen; and a pathogen database ( 34 ) storing infectious transmission information for at least the tracked pathogen including one or more transmission modes for the tracked pathogen and at least one node residency time for the tracked pathogen. The non-transitory storage medium includes instructions readable and executable by the at least one electronic processor to perform an infectious disease transmission tracking method ( 100 ) including: computing a pathway ( 35 ) on the map of at least one infected node using locations of the tag associated with the infected node received from the RTLS wherein an infected node has a non-zero infection likelihood respective to the tracked pathogen which satisfies an infected criterion; computing an infectious zone ( 36 ) on the map along the pathway using the infectious transmission information stored in the pathogen database; for each node contacting the infectious zone, adjusting the infection likelihood of the contacting node in the nodes database based on at least the infectious transmission information for the tracked pathogen and designating the contacting node as an infected node if the updated infection likelihood of the contacting node satisfies the infected criterion.

CROSS-REFERENCE TO PRIOR APPLICATIONS

This application is the U.S. National Phase application under 35 U.S.C.§ 371 of International Application No. PCT/EP2018/069575, filed on Jul.19, 2018, which claims the benefit of U.S. Patent Application No.62/537,996, filed on Jul. 28, 2017. These applications are herebyincorporated by reference herein.

FIELD

The following relates generally to the patient monitoring arts, patienttreatment facility monitoring arts, infection containment arts, trackingsystem arts, and related arts.

BACKGROUND

Infection control is the discipline concerned with combating hospitalacquired or healthcare-associated infection (HAI). HAI is an infectionwhose development is favored by a hospital environment, nursing home,rehabilitation facility, clinic, or other clinical settings. Thisinfection is spread to the patient in the clinical setting by a numberof means. Health care staff can spread infection, contaminatedequipment, bed linens, or air droplets. The infection can originate fromanother infected patient or hospital staff member, or in some cases, thesource of the infection cannot be determined.

According to the Centers for Disease Control and Prevention in the U.S.,there were an estimated 722,000 HAI incidents in U.S. acute carehospitals in 2011. About 75,000 hospital patients with HAIs died duringtheir hospitalizations. More than half of all HAIs occurred outside ofthe intensive care unit (see, e.g.,http://www.cdc.gov/HAI/surveillance/). Preventing HAIs could save $25-32billion in the US alone (see, e.g., Scott RD II, “The direct medicalcosts of healthcare-associated infections in U.S. hospitals and thebenefits of prevention”, in Diseases CCfI, ed.: Centers for DiseaseControl and Prevention: 1-13).

Most countries lack surveillance systems for health care-associatedinfections. Those that do have systems often struggle with thecomplexity and lack of standardized criteria for diagnosing theinfections. While this makes it difficult to gather reliable globalinformation on health care-associated infections, results from studiesclearly indicate that each year, hundreds of millions of patients areaffected by health care associated infections around the world (see,e.g.,http://www.who.int/gpsc/country_work/gpsc_ccisc_fact_sheet_en.pdf).Moreover, recent outbreaks of infectious diseases such as Ebola, MERS,SARS and H1N1 have highlighted the need by healthcare institutions tofollow proper infection control protocols.

The World Health Organization (WHO) has strict guidelines on protocolsthat need to be followed to minimize the risk of the spread of infection(see, e.g.,http://www.wpro.who.int/publications/docs/practical_guidelines_infection_control.pdf;andhttp://www.who.int/csr/resources/publications/WHO_CDS_EPR_2007_6c.pdf).While some of the guidelines are easy to implement and follow, there areothers that are hard to implement. For example, there are protocols thatrequire a healthcare worker to follow a different set of protocols whenthe distance between the worker and an infected patient is less than 1meter. Apart from adhering to such distance restrictions based on visualobservations, hospitals today do not utilize any monitoring systems toensure that the recommended protocols are strictly implemented.Furthermore, in the event of an infectious disease breakout, the usualapproach to trace the movements of all individuals who may have come incontact with the infected patient is purely based on memory.

A Real-Time Locating System (RTLS) can be used to track individualpatients and healthcare workers for the purpose of infection control.Previous efforts have been made regarding aspects of this compliance(see, e.g., US Pat. Pub. No. 2012/0112883).

The following discloses new and improved systems and methods.

SUMMARY

In one disclosed aspect, an infectious disease transmission trackingsystem includes a real-time locating system (RTLS) configured to tracklocations of tags in a monitored area. At least one electronic processoris in operative communication with the RTLS to receive locations of tagsin the monitored area. A non-transitory storage medium stores, a map ofthe monitored area; a nodes database storing information on nodes inwhich each node is a person, a mobile object, or a map zone and thenodes database stores information on the nodes including at least (i) anidentification of each node as a person, a mobile object, or a map zone,(ii) an identification of a tag associated with each node that isidentified as a person or a mobile object, (iii) locational informationon the map for each node that is identified as a map zone, and (iv) aninfection likelihood for each node with respect to a tracked pathogen;and a pathogen database storing infectious transmission information forat least the tracked pathogen including one or more transmission modesfor the tracked pathogen and at least one node residency time for thetracked pathogen. The non-transitory storage medium includesinstructions readable and executable by the at least one electronicprocessor to perform an infectious disease transmission tracking methodincluding: computing a pathway on the map of at least one infected nodeusing locations of the tag associated with the infected node receivedfrom the RTLS wherein an infected node has a non-zero infectionlikelihood respective to the tracked pathogen which satisfies aninfected criterion; computing an infectious zone on the map along thepathway using the infectious transmission information stored in thepathogen database; for each node contacting the infectious zone,adjusting the infection likelihood of the contacting node in the nodesdatabase based on at least the infectious transmission information forthe tracked pathogen and designating the contacting node as an infectednode if the updated infection likelihood of the contacting nodesatisfies the infected criterion.

In another disclosed aspect, a non-transitory computer-readable storagemedium includes a map database storing a map of a monitored area. Anodes database stores information on nodes in which each node is aperson, a mobile object, or a map zone and the nodes database storesinformation on the nodes including at least (i) an identification ofeach node as a person, a mobile object, or a map zone, (ii) anidentification of a tag associated with each node that is identified asa person or a mobile object, (iii) locational information on the map foreach node that is identified as a map zone, and (iv) an infectionlikelihood for each node with respect to a tracked pathogen. A pathogendatabase stores infectious transmission information for at least thetracked pathogen including one or more transmission modes for thetracked pathogen and at least one node residency time for the trackedpathogen. The storage medium also includes instructions readable andexecutable by at least one electronic processor to perform an infectiousdisease transmission tracking method including: receiving, from one ormore tag readers of a real time location system (RTLS), locations of oneor more tags of the RTLS in the monitored area; computing a pathway onthe map of at least one infected node using locations of the tagassociated with the infected node received from the RTLS in which aninfected node has a non-zero infection likelihood respective to thetracked pathogen which satisfies an infected criterion; computing aninfectious zone on the map along the pathway using the infectioustransmission information stored in the pathogen database; for each nodecontacting the infectious zone, adjusting the infection likelihood ofthe contacting node in the nodes database based on at least theinfectious transmission information for the tracked pathogen anddesignating the contacting node as an infected node if the updatedinfection likelihood of the contacting node satisfies the infectedcriterion.

In another disclosed aspect, an infectious disease transmission trackingsystem includes a real-time locating system (RTLS) including tags andtag readers in which the tag readers are distributed through a monitoredarea and are configured to track locations of the tags in the monitoredarea. At least one electronic processor is in operative communicationwith the RTLS to receive locations of tags in the monitored area. Anon-transitory storage medium stores a map of the monitored area. Anodes database stores information on nodes in which each node is aperson, a mobile object, or a map zone and the nodes database storesinformation on the nodes including at least (i) an identification ofeach node as a person, a mobile object, or a map zone, (ii) anidentification of a tag associated with each node that is identified asa person or a mobile object, (iii) locational information on the map foreach node that is identified as a map zone, and (iv) an infectionlikelihood for each node with respect to a tracked pathogen. A pathogendatabase stores infectious transmission information for at least thetracked pathogen including one or more transmission modes for thetracked pathogen and at least one node residency time for the trackedpathogen. The storage medium includes instructions readable andexecutable by the at least one electronic processor to perform aninfectious disease transmission tracking method including: computing apathway on the map of at least one infected node using locations of thetag associated with the infected node received from the RTLS wherein aninfected node has a non-zero infection likelihood respective to thetracked pathogen which satisfies an infected criterion; computing aninfectious zone on the map along the pathway using the infectioustransmission information stored in the pathogen database; for each nodecontacting the infectious zone, adjusting the infection likelihood ofthe contacting node in the nodes database based on at least theinfectious transmission information for the tracked pathogen anddesignating the contacting node as an infected node if the updatedinfection likelihood of the contacting node satisfies the infectedcriterion, the adjusting of the infection likelihood of the contactingnode in the nodes database being determined by the equation: p=f(d, a,t, s, T, H, o, i, h), where d is a distance between two nodes; a is airflow characteristics between the two nodes; t is a time passed since oneof the nodes was last in contact with the pathogen of interest; s is atype of surface of the node, T is a temperature in the vicinity of thenode; H is a humidity value in the vicinity of the node; o is an orderof node from the node which is considered to be the original source ofinfection; I is a number of times that the nodes have encountered eachother since first getting infected; and h is an execution of hygieneregime.

One advantage resides in providing an improved RTLS-based infectiousdisease transmission tracking or monitoring system that addressesspatial and temporal aspects of infectious disease management.

Another advantage resides in providing an RTLS-based infectious diseasetransmission tracking or monitoring system with improved fidelity to WHOguidelines for infection control.

Another advantage resides in providing an RTLS-based infectious diseasetransmission tracking or monitoring system that generates quantifiabledata regarding the spread of an infection, rather than word of mouthtestimony from hospital staff.

Another advantage resides in providing an RTLS-based infectious diseasetransmission tracking or monitoring system that provides an RTLS systemwith contact tracing infection data, rather than data from medicalrecords.

Another advantage resides in providing an RTLS-based infectious diseasetransmission tracking or monitoring system to track the spread ofinfections by computing a risk of infection in real time includingtaking into account different disease transmission pathways withdifferent spatial ranges.

Another advantage resides in providing an RTLS-based infectious diseasetransmission tracking or monitoring system to dynamically track thespread of infections by computing a risk of infection in real timeincluding taking into account decreasing likelihood of infectioustransmission in situations where a disease transmission vector has alimited pathogen viability lifetime.

A given embodiment may provide none, one, two, more, or all of theforegoing advantages, and/or may provide other advantages as will becomeapparent to one of ordinary skill in the art upon reading andunderstanding the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure may take form in various components and arrangements ofcomponents, and in various steps and arrangements of steps. The drawingsare only for purposes of illustrating the preferred embodiments and arenot to be construed as limiting the invention.

FIG. 1 diagrammatically shows a Real-Time Locating System (RTLS)-basedinfectious disease tracking system according to one aspect;

FIG. 2 shows an exemplary flow chart depicting aspects of operation ofthe system of FIG. 1;

FIG. 3 illustratively shows an example use of the tracking system ofFIG. 1;

FIG. 4 illustratively shows another example use of the tracking systemof FIG. 1;

FIG. 5 shows a graph of data related to pathogens tracked by thetracking system of FIG. 1; and

FIG. 6 shows a graph showing data of probabilities of nodes havingpathogens tracked by the tracking system of FIG. 1.

DETAILED DESCRIPTION

The following discloses approaches for tracking or monitoring oftransmission of hospital (or healthcare facility) acquired infection(HAI). The disclosed approaches employ a Real-Time Locating System(RTLS) for spatially and temporally mapping contact pathways.

The following more particularly relates to the tracing of contacts of aninfected person in the hospital using an RTLS to track infected (orpotentially infected) persons. RTLS are currently deployed in somehospitals for purposes such as tracking patients, monitoring deploymentof medical resources such as mobile assets (e.g. mobile x-ray devices,beds), or so forth. In principle, an RTLS can be used to track aninfected patient and identify other persons with whom the infectedpatient comes into contact; and then to track persons those individualscome into contact with, and so forth, so as to track the infectioustransmission pathways of a pathogen during an infectious outbreak.

However, the use of RTLS for this purpose has certain difficulties.First, the RTLS has limited spatial resolution, which may vary bylocation. For example, the RTLS may identify the location of a patientwith high spatial resolution in a patient hospital room, but withcoarser resolution in hallways. The range of infectious transmission canalso vary depending upon the transmission pathway (contact, airborne, ordroplets), and the likelihood of transmission may depend on exposuretime. Second, RTLS tracking of infected individuals does not take intoaccount the potential for temporally delayed transmission. For example,if an infected person occupies a waiting room for some time interval andthen leaves, and thereafter a nurse cleans the waiting room, that nursemay become infected, e.g. by way of pathogenic contamination of surfacesin the waiting room. Yet, the infected person and the nurse never cameinto contact or even close proximity to each other.

The disclosed approach overcomes these difficulties and others. Thedisclosed tracking estimates the most likely path of the patient, e.g.in hallways where the RTLS provides limited tracking. An infectious zoneis defined along this path, e.g. one meter to either side of the path inthe case of droplet transmission. The infectious zone may be adjustedbased on additional information. For example, if the patient stays in asingle location for some time, the zone may be expanded based on thatextended occupancy, or may be expanded to fill the entire room.

The disclosed tracking approach also extends the concept of“transmission” to more broadly encompass transmission between pairs of“nodes”, where a node may be a person, but also may be a location (i.e.,spatial “zone”) or an asset or other mobile object (e.g. a mobile x-raydevice, patient bed, or so forth). Thus, when a patient occupies awaiting room there will be a transmission likelihood from the patient tothe waiting room; when the nurse later cleans the waiting room therewill be a transmission likelihood from the waiting room to the nurse.The transmission tracking is also dynamic based on known timeconstraints on transmission. Thus, for example, if a known pathogen cancontaminate surfaces which then remain infectious for two hours, thenthe waiting room may have its likelihood of infection reset to zeroafter two hours (and optionally its likelihood of infection may be setto decay to zero as a function of time to even more accurately representthe actual transmission probability over time).

Other available information can also be taken into account in dynamictracing of infectious contact pathways. For example, some RTLS have thecapability to monitor usage of sanitation devices such as sanitary soapdispensers. If this is available, then if a nurse interacts with apatient in the hospital room and the sanitary device in the patient'shospital room is not used, this information from the RTLS can be used toincrease the likelihood of infectious transmission to the nurse.Temperature and/or humidity may be monitored automatically, and thisinformation may be taken into account in estimating the transmissionlikelihood (for example, if residency of a known pathogen on surfaces ishumidity-dependent). As another example, if two nodes are connected byan HVAC circuit that does not have HEPA filters capable of filtering outthe pathogen, then the likelihood of infection between these nodes maybe increased based on this information.

Embodiments of the disclosed infectious contact tracking system includevarious components. The RTLS may be embodied by a tag/reader systememploying RFID, WiFi, infrared, ultrasound, or other tag readingtechnologies. A map of the hospital is provided, including delineationof the spatial zones monitored by the RTLS along with other salientinformation such as auxiliary monitoring stations (e.g. temperaturesensors, humidity sensors, sanitary device usage sensors), types ofsurfaces in the room (relevant to surface-mediated transmission), HVACcircuit pathways, and/or so forth. A computer is programmed byinstructions stored on a non-transitory storage medium (e.g. hard drive,optical disk, FLASH memory or other electronic storage medium, or soforth) and readable and executable by the computer to perform infectiouscontact tracing as outlined above using data from these devices. Theoutput may, for example, be a list of nodes (persons, locations, andassets) with likelihoods of infection, which may be time-dependent. Topromote rapid assessment of the most likely nodes to be infected, aninfected criterion may be applied, by which only those nodes whichsatisfy the infected criterion are listed. It should be noted that insuch an approach, the infected criterion should not be viewed asdefinitively identifying nodes which are infected, but rather should beviewed as identifying nodes whose likelihood of infection issufficiently high that follow-up testing should be performed (e.g.testing the individual for the infection; swiping surfaces of the mobileobject to test for pathogen contamination, performing testing of air ina spatial zone meeting the infected criterion, or so forth).Advantageously, using such an infected criterion provides identificationof the persons, objects, and/or places most likely to be infectedthereby providing a principled basis for efficient allocation of limitedtesting resources.

The RTLS systems of the following are described now in more detail. RTLSsystems provide immediate or real-time tracking and management ofmedical equipment, staff and patients. This type of solution enableshealthcare facilities to capture workflow inefficiencies, reduce costs,and increase clinical quality. RTLS systems are comprised of varioustags (which may be referred to by other nomenclatures, e.g. as badges),platforms (Wi-Fi, Infrared, Ultrasound, and others), hardwareinfrastructure (tag readers and tag exciters, in the case of passivetags that must be externally energized) and other components (e.g.server computers and non-transitory storage medium storing softwarereadable and executable by the server(s) to perform RTLS operations suchas tracking tagged entities). Typically, an RTLS consists of eitherspecialized fixed location sensors (i.e. tag readers) receiving wirelesssignals from small ID badges or other types of tags attached toequipment or persons, or fixed beacons (i.e. RF, infrared or ultrasoundbeacons) providing location information to ID badges or other types oftags attached to equipment or persons. Each tag transmits its own uniqueID in real time, and depending on the technology chosen, the systemlocates the tags and therefore the location of the tagged entities.Depending on the solution, varying degrees of spatial granularity can beachieved. Basic RTLS solutions can enable tracking in a hospital's unitor floor, whereas clinical-grade systems may achieve finer spatialgranularity on the level of room, bed, bay, and even shelf-leveltracking. Moreover, the spatial granularity may vary for differentlocations depending upon the type and distribution/density of tagreaders. For example, if one or more tag readers or beacons is installedin each patient room, which has relatively small spatial extent, thenthe tracking precision in patient rooms may be high. By contrast, asmaller density of tag readers or beacons may be deployed along hospitalcorridors, providing more coarse spatial resolution in corridors.

In the disclosed RTLS-based infectious disease transmission tracking ormonitoring systems, the RTLS systems are used to track diseasetransmission with closer fidelity to WHO regulations regardinginfectious disease control. The WHO outlines protocols to prevent thespread of infections by three different transmission pathways: directcontact; airborne transmission; and transmission by droplets. Contactprecautions are designed to reduce transmission through direct patientcontact and indirect contact with items in the patient's environment.Airborne precautions are designed to reduce the transmission of diseasesspread by an airborne route in which transmission occurs when dropletshaving nuclei of less than 5 micron in size are disseminated in the air.These particles can remain suspended in the air for long periods oftime. Droplet precautions are designed to reduce transmission of diseaseby adequate contact between a susceptible person and large particledroplets (i.e., greater than 5 microns). These droplets are usuallygenerated from the infected person during coughing or sneezing. Largeparticles typically remain suspended in the air for limited period oftime and settle within 1 m of the source.

When taking these precautions into account, it is evident that aninfection can spread through: (1) direct physical contact with theinfected patient; (2) immediate contact over air due to close proximity(may also be shared ventilation between rooms); (3) delayed contact withair that has been infected by infected patient; (4) indirect physicalcontact with an individual who has been in direct physical contact withthe infected patient; and (5) indirect physical contact with an objectwhich has been in direct physical contact with the infected patient.Apart from the first two modes of spreading infection, which occurinstantaneously, the remaining methods involve the spread of infectionover an extended duration of time. For example, an object that has beentouched by an infected patient might remain infectious for the next fivehours. It should also be noted that a given pathogen may betransmittable via only a subset of these pathways, e.g. some pathogenscannot be transmitted by airborne transmission; and moreover, theinfectious lifetime for a given delayed pathway depends on the type ofpathogen and the type of environmental conditions the pathogen isexposed to.

In the event of the spread of an infection or the outbreak of aninfectious disease, it is important for hospital administrators to knowseveral factors, including the source of the infection, the manner inwhich the infection spread, the individuals responsible for spreadingthe infection, the individuals who are currently infected (or have ahigh likelihood of being infected), the time at which a particularindividual became infected, portions of a hospital that need to bedisinfected, among others. In order to determine these factors, mosthospital administrators depend on their pre-existing knowledge of thevarious workflows/processes within the hospital. They also might referto hospital records which contain information about patients andclinical/non-clinical staff who were involved in caring for the infectedindividual. Interviews are also performed with all patients andcaregivers who may have interacted with each other at some point in thepast in order to trace all possible points of contact through which theinfection may have spread.

There are several problems with this approach. First, contact tracing isbased on highly coarse-grained data (e.g. information gathered frominterviews is purely based on memory). Second, gathering informationfrom medical records is also not granular enough to provide contacttracing data that is accurate enough to easily track how an infectionhas spread or which rooms in a hospital need to be disinfected. Third,pathogens can survive outside the body for extended time periods. Thismeans that a room can remain infected long after the source of infectionhas left the room. This makes contact tracing based on informationderived from interviews (i.e. memory) extremely difficult. Fourth, it isimpossible to track the spread of infections or compute the risk ofinfection spread in real-time.

With reference to FIG. 1, an illustrative infectious diseasetransmission tracking system 10 is shown. The tracking system 10includes a real-time locating system (RTLS) 12 with radiofrequencyidentification (RFID) tags 14 and RFID tag readers 16. The tag readers16 are distributed through a monitored area A and are configured totrack locations of the tags 14 in the monitored area. For example, thetags 14 are attached or otherwise secured to one or more nodes 18 (e.g.,a patient, a medical professional, a mobile object such as a piece ofmedical equipment, a zone in the monitoring area A, and the like). Thetags 14 may be referred to by other terms, e.g. badges, tracking chips,et cetera—the term “tag” as used herein is intended to encompass suchalternative nomenclatures. The tag readers 16 are distributed throughoutthe monitored area A where persons or mobile objects to be tracked maytraverse (e.g., in a patient room, in a hallway, at a workstation of amedical professional, and the like). In some examples, the monitoredarea A can be a two-dimensional area (i.e., a single floor of ahospital) while in other examples, the monitored area can be athree-dimensional area (i.e., multiple floors of a hospital). The tagreaders 16 are configured to receive location data from thecorresponding tags 14, thereby allowing the tag readers to track acorresponding node 18. In the simplest design, a tag reader may have anoperational range, e.g. five meters, and any tag detected by that tagreader is known to be within a five meter radius of the tag reader. Inother designs, two or three or more tag readers with overlappingoperational ranges may operate in concert to more precisely locate atag, e.g. using triangulation or the like. In yet other designs, asingle tag reader may provide directional information using a phasedarray transducer, a rotating transducer, or so forth. These are merelyillustrative examples of RTLS ranging and angulating technologies, andmore generally the RTLS 12 may use any suitable tracking technology toprovide real time locational information for the tags present in themonitored area A. In addition, the tag readers 16 are configured toreceive tag identifying information from the corresponding tag 14 inorder to determine the particular tag 14 (and hence the correspondingnode 18) being tracked.

The tag identifying information may take various forms, e.g. in activetag designs the tag 14 includes an on-board battery-poweredmicroprocessor or microcontroller and associated non-transitory memory(e.g. a FLASH, PROM, or other electronic memory chip) that stores a tagidentifier number or the like which the tag 14 transmits to the tagreader 16. In a passive tag design, radio frequency energy transmittedby the tag reader 16 to the tag 14 powers the tag to drive it totransmit its tag identifier. In less sophisticated designs, each tag maytransmit at a different frequency and the tag is identified by itsresponse frequency. These are merely illustrative examples of tagidentification technologies, and more generally the RTLS 12 may use anysuitable tag identification technology to provide the tag readers 16with real time identification of detected/tracked tags. Optionally, theRTLS 12 may be compliant with an industry-defined RTLS standard, e.g.ISO/IEC 24730-1 or a variant thereof.

In other embodiments, the RTLS 12 can include an infrared identification(IRID) system including one or more tags 15; a beacon or tag reader 17;a radiofrequency tracking communication station 19; and a server 21. Thetags 15 are configured to be worn by a hospital staff member or apatient or attached to a node 18. The tags 15 include an IR receiver andRF transceiver (not shown). The beacon 17 is configured for attachmentto a ceiling of the monitoring area A and covers a particular zone inthe monitoring area by broadcasting an IR signal. The beacon 17 isconfigured to broadcast an IR signal with a unique ID representing aparticular zone. An identification (ID) is mapped to a particular zonein the monitoring area A. The communication station 19 is configured tocommunicate with the tags 15 via RF signals. In use, the beacon 17 isconfigured to broadcast a unique IR ID representing a zone in themonitoring area A. The corresponding tag 15 in the zone receives the IRID from the beacon 17 via the IR receiver. The tag 15 is configured toreport the sensed IR ID to the communication station 19 via an RFsignal. The star 19 is configured to report the IR ID to the server 21,which is configured to map the IR ID to the corresponding zone (whichcan be set by an installer of the RTLS 12). In other embodiments, theRTLS 12 can include any other location identification system, forexample using RF, ultrasound, infrared or vision technology.

The illustrative infectious disease transmission tracking system 10 alsoincludes a computer or imaging workstation or other electronic dataprocessing device 20 with typical components, such as at least oneelectronic processor 22, at least one user input device (e.g., a mouse,a keyboard, a trackball, a device with an embedded screen such as atablet, a smartphone, a smartwatch, an alternate reality/virtual realityheadset or goggles, and/or the like) 24, and a display device 26 onwhich an interactive abnormality/lesion insertion graphical userinterface (GUI) (not shown) can be displayed. In some embodiments, thedisplay device 26 can be a separate component from the computer 20.

The at least one electronic processor 22 is operatively connected with anon-transitory storage medium (not shown) that stores instructions whichare readable and executable by the at least one electronic processor 16to perform an infectious disease transmission tracking method or process100, and to perform other operations as appropriate (e.g. dataacquisition from the RTLS 12). The non-transitory storage medium may,for example, comprise a hard disk drive, RAID, or other magnetic storagemedium; a solid state drive, flash drive, electronically erasableread-only memory (EEROM) or other electronic memory; an optical disk orother optical storage; various combinations thereof; or so forth. Insome examples, the infectious disease transmission tracking method orprocess 100 may be performed by cloud processing.

The non-transitory storage medium can include one or more databases. Forexample, the non-transitory storage medium stores a map database 28containing a map 30 of the monitored area A. The map 30 can include afloorplan layout of a hospital, and may also include information such asHVAC linkages between spatial zones, information on sanitary dispensermonitors (if monitored by the RTLS 12), and so forth.

The non-transitory storage medium further stores a nodes database 32containing information related to the nodes 18. The nodes 18 can be ofthree types in the illustrative embodiment: patient and staff nodes,mobile object nodes such as a piece of medical equipment, and map zonenodes corresponding to spatial zones or areas defined in the monitoringarea A (or in the map 30 of that area A). Advantageously, and as furtherdetailed herein, providing for these three types of nodes enablestracking of infectious pathogen transmission via direct contact (bytracking intersections of nodes representing an infected person and acontacting person), via surface mediation (by tracking contact of aninfected person with a mobile object node and subsequent contact of themobile object node with a second person), or via airborne or dropletpathways (by tracking contact of an infected person with a map zone nodeand subsequent contact of a second person with that map zone node). Asused herein, the term “mobile unit” or “mobile object” (and variantsthereof) refer to objects expected to occasionally move from one spatialzone to another, for example by being carried by a person. Examples ofmobile objects include various medical assets such as mobile x-rayunits, mobile ultrasound machines, intravascular delivery systems thatcan be expected to occasionally be moved from one patient room toanother, feeding pumps, infusion pumps, or so forth. In addition, thenodes database 32 may store information related to types of mobileobjects so as to estimate residency of the pathogen on the surface. Forexample, an object with shiny metal surfaces may have a much shorterpathogen residency than an object with porous surfaces. In addition, asused herein, a zone in the monitoring area A (i.e., a map zone) refersto be an entire room or a portion of a room of a hospital, or may besome other spatial zone such as a hallway. In addition, these zones maybe classified according to location in the monitoring area A. Thechoices or delineations of map zones for the purpose of pathogentransmission tracking is dependent upon factors such as the spatialresolution of the RTLS 12, natural spatial delineations defined byarchitecture (e.g. a small room may sensibly be chosen as a single mapzone) or usage (e.g. in a waiting room it may make sense to define thewaiting area containing the patient chairs as one map zone and thereceptionist area as a different map zone), or so forth.

The nodes database 32 stores information related to the nodes 18. In oneexample, the nodes database 32 stores information related to anidentification of each node 18 as a person, a mobile object, or a mapzone. In another example, the nodes database 32 stores informationrelated to an identification of a tag 14 associated with each node 18that is identified as a person or a mobile object. In a further example,the nodes database 32 stores locational information on the map 30 foreach node 18 that is identified as a map zone. In yet another example,the nodes database 32 stores information related to an infectionlikelihood for each node with respect to a tracked pathogen. In someembodiments, the infection likelihood can be a continuous or steppedvalue ranging between zero and one, with a value of one being indicativeof near-certain infection and a value of zero being indicative of nearcertainty of no infection, and an intermediate value such as 0.7 beingindicative of an intermediate likelihood of infection. In otherembodiments, the infection likelihood can be a binary value of eitherzero (not infected) or one (infected).

In a further example, the non-transitory storage medium can include apathogen database 34 configured to store transmission information for atleast a tracked pathogen. The transmission information can include oneor more transmission modes (e.g., contact, airborne, droplets, and thelike) for the tracked pathogen. As used herein, the term “pathogen” (andvariants thereof) refers to a single pathogen, a class of pathogens, oran unknown pathogen that is assigned conservative estimate values forthe transmission information in the pathogen database 34 (i.e.,conservative being likely to overestimate infection likelihoods). If agiven pathogen is not capable of transmission by a particular pathway(e.g. cannot be transmitted by the airborne pathway) then the pathogendatabase 34 suitably stores this information. In addition the pathogendatabase 34 is configured to store at least one node residency time forthe tracked pathogen. The residency time, in some examples, can be afunction of the transmission mode. For example, a pathogen may have a(typically longer) airborne contamination residency time versus a(typically shorter) droplet contamination residency time, and may havesome other residency time for surface contamination (which may befurther divided based on the type of surface). In other examples, theresidency time can be dependent on further information about the nodes18 stored in the nodes database 32. In further examples, the residencytime can be a function of temperature and humidity (among otherfactors), as well as different types of nodes 18 (i.e. persons, objects,or zones) that naturally have different residency times. The informationon pathogens stored in the pathogen database 34 is preferably derivedfrom the professional epidemiology literature, and may be occasionallyupdated to reflect the most current medical knowledge. In some examples,pathogen information can be entered into the pathogen database 34. Forexample, a user may enter this pathogen information if the user suspectsthat there has been an infection outbreak in instances where thehospital hasn't experience problems with a particular pathogen beforeand is experiencing the pathogen for the first time.

It will be appreciated that the workstation 20 can be in electroniccommunication with one or more other databases (not shown) (e.g., anelectronic medical record (EMR) database, a picture archiving andcommunication system (PACS) database, and the like), among others. Inaddition, these databases 30, 32, 34 may be a single database, or a pairof databases.

As shown in FIG. 1, the electronic processor 22 is programmed to performRTLS-based infectious disease transmission tracking. For example, theelectronic processor 22 is in operative communication with the RTLS 12to receive locations of the tags 14 in the monitored area A from the tagreaders 16 of the RTLS. The non-transitory medium includes instructionsreadable and executable by the at least one electronic processor 22 toperform an infectious disease transmission tracking method 100. In someembodiments, the same electronic processor 22 also performsimplementation of software components of the RTLS 12; while in otherembodiments software components of the RTLS 12 are implemented on adifferent computing device or system (not shown).

With reference now to FIG. 2 and with continuing reference to FIG. 1, anillustrative embodiment of the infectious disease transmission trackingmethod 100 is diagrammatically shown as a flowchart. At 102, a pathwayis computed on the map 30 of at least one infected node 18 usinglocations of the tag 14 associated with an infected node received fromthe RTLS 12. For example, an infected node 18 has a non-zero infectionlikelihood respective to the tracked pathogen which satisfies aninfected criterion. In some examples, the infected criterion can involvea user (e.g., a medical professional) selecting, via the use inputdevice 24 the infected node 18 in the nodes database 32, and labelingthe infected node as having a percentage of infection likelihood (e.g.,25%, 50%, 100%, and so forth). Once all the infected nodes 18 have beenlabeled, as shown in FIG. 4, a pathway 30 that passes through each ofthe infected nodes can be determined.

FIG. 3 shows an example of the map 30 (or one floor of the map 30 in thecase of a multi-floor map). The map 30 shows several zones Z (delineatedby dashed lines) in which a tag reader 16 or beacon 17 may be located.Each zone Z represents a spatial area within which a tag 14 can bedetected and localized by the RTLS 12. Said another way, the RTLS 12 canidentify, at any given time, within which zone Z a given tag is located.As shown in FIG. 3, the tag readers 16 track the location of acorresponding node 18 at a first location 1 in a first zone to a secondlocation 2 in a second zone. A pathway 35 is then determined and mappedbetween the first and second locations. In general, the determination ofthe pathway 35 is made based on the time series of locations of the tag14 corresponding to the tracked node 18; however, additional pathwayapproximation processing may be employed for example, if the node 18traverses an area that is not covered by the RTLS 12, then processingmay be employed to interpolate the pathway 35 in the area not covered bythe RTLS 12, e.g. assuming an average speed of the node 18 through theuncovered area. In other examples, the pathway 35 can be smoothed tomore closely represent a person's movement.

At 104, an infectious zone 36 is computed on the map 30 along thepathway 35 using the infectious transmission information stored in thepathogen database 34. As shown in FIG. 3, an infectious zone 36 ofapproximately 1 m is marked out on either size of the pathway 35. The 1m boundary is based on the criteria defined by the WHO for preventingthe spread of infections. The width of the infectious zone 36 around thepathway 35 may be adjusted based on various factors, such as the timethe infected node 18 spends in each map zone (the infectious zone 36 maybe widened if the infected node 18 spends more time in a given mapzone), or based on the airborne residency of the particular pathogenwhose transmission is being tracked (e.g., the infectious zone 36 may bewidened if the pathogen has a longer airborne residency, or may benarrowed if the pathogen has a shorter airborne residency or cannot betransmitted by the airborne pathway).

The adjustment can compensate for the possibility that certaininfectious areas will be missed. In order to prevent this a user canspecify a larger safety margin than the 1 m specified by the WHO. Thiswould reduce or eliminate the chances of missing individuals who havebeen infected, thereby resulting in lower false negatives. (On the otherhand, this action increases the chances of identifying unaffectedindividuals as infected individuals, thereby increasing falsepositives). The RTLS 12 also allow previously collected location data tobe post-processed using different danger zone thresholds in order tocompute different risk models which identify which individuals might beinfected or be responsible for spreading infection.

At 106, for each node 18 contacting the infectious zone 36, theinfection likelihood of the contacting node in the nodes database 28 isadjusted based on at least the infectious transmission information forthe tracked pathogen and designating the contacting node as an infectednode if the updated infection likelihood of the contacting nodesatisfies the infected criterion. A “contacting node” is one which whoselocation intersects the infectious zone 36 in a time interval over whichthe infectious zone 36 is deemed to be contaminated by the trackedpathogen. The time interval for pathogen transmission depends on theresidency of the pathogen contamination on surfaces of the mobile object(for mobile object nodes) or on residency of pathogen contamination inthe air or on surfaces in the case of a map zone node. Likewise, in thecase of a node representing a person, there is usually an asymptomaticincubation period during which the person, having become infected, iscontagious but does not exhibit any symptoms. If this incubation periodpasses without the person showing symptoms, then it may be concluded theperson was not infected, and the node infection likelihood can be resetto zero.

To account for pathogen contamination residency time, in someembodiments, a time-dependent infection likelihood value is determined,for each node 18 in a list of nodes, in which the corresponding node isdetermined to have an infection likelihood which decreases to zero overtime, with the likelihood reaching zero at the end of the incubationperiod for a human node (assuming the human remains asymptomatic) or atthe end of the pathogen contamination lifetime for a mobile object ormap zone node. In the case of a human node, if the human becomessymptomatic then the infection likelihood for that human node can bereset to one (certainly infected) and this unity infection likelihoodcan be propagated back in time to the point in time the human nodeacquired the infection (e.g. came into contact with the infectious zone36). The infection likelihood of the nodes 18 decreases over time, andultimately can end up at zero. In other examples, the time-dependentvalue is set to zero upon receiving an indication that the correspondingnode 18 is no longer infectious (e.g. after passage of the incubationperiod with the person remaining asymptomatic, or after passage of thepathogen residency time on a surface or as airborne contamination).

In further embodiments, the time-dependent value of at least one of thenodes 18 is increased upon receiving, from one of the tag readers 16,multiple measurements that the pathway 32 between two of thecorresponding nodes tracked by the tag reader remains unchanged. Inother words, when a node 18 has stopped moving (e.g., when the node is apatient being moved through the hospital and the medical professionalmoving the patient stops for a moment), the distance between thecorresponding tag 14 (or 15) and tag reader 16 (or the beacon 17 and thecommunication system 19) is the same. When this occurs, thetime-dependent value is increased to make sure the RTLS 12 knows whenthe node 18 (i.e., the patient) is moving again. This is illustrated inFIG. 4. When the RTLS 12 detects that a node 18 has not emerged from azone within a particular pre-defined time (that is, specified for thatparticular zone) the infectious zone 36 is extended to cover the entirearea, as shown by enlarged zones Y.

In other embodiments, the RTLS 12 includes monitoring of usage ofsanitary stations 38 disposed in the monitored area A, and the map 30includes locations of the sanitary stations monitored by the RTLS. Inthis embodiment, the adjusting of the infection likelihood of thecontacting node 18 in the nodes database 32 is further based onmonitored usage of a sanitary station 38 at contact with the infectiouszone 36.

In further embodiments, the adjusting of the infection likelihood of thecontacting node 18 in the nodes database 32 is functionally dependent onseveral factors, including at least a distance between two nodes; airflow characteristics between two nodes; a time passed since one of thenodes was last in contact with the pathogen of interest; a type ofsurface of the node, a temperature in the vicinity of the node; ahumidity value in the vicinity of the node; an order of node from thenode which is considered to be the original source of infection; anumber of times that the nodes have encountered each other since firstgetting infected; and an execution of hygiene regime.

For example, as the RTLS 12 monitors the location of all nodes 18 inreal-time, it continuously computes checks to see which pair of nodesshould be connected by an edge and, if so, the at least one electronicprocessor 22 is programmed to assign a weight to the edge. The weightassigned to a node 18 corresponds to the probability that one node caninfect the other. If both nodes 18 are in a position to infect eachother, the edge is assigned the higher probability, i.e. weight. An edgeis assigned between two nodes if the probability of one node infectinganother is higher than a particular threshold p, where p (the weightassigned to the edge) is computed as follows:p=f(d,a,t,s,T,H,o,i,h),  (1)where d: is a distance between the two nodes (i.e., a closest possibledistance between the nodes); a is air flow characteristics (e.g. airvelocity/pressure/etc.) between two nodes if they are connected througha common HVAC system; t is a time that has passed since the node waslast in contact with the pathogen of interest; s is a type of surface(e.g. non-porous/textile/etc.) that predominantly defines the node; T isa temperature in the vicinity of the node; H is a humidity in thevicinity of the node; o is an order of node from the node which isconsidered to be the original source of infection; i is a number oftimes that the nodes have encountered each other since first gettinginfected; and h is an execution of hygiene regime (e.g. when a nurseuses a hand sanitizer, a room is disinfected, etc.). FIG. 5 shows agraph illustrating how p might vary over time (t) for differentpathogens, given specific values for d, a, s, T, H, o, i and h. As shownin FIG. 5, the “top” curve is data for a first pathogen A, and the“bottom” curve is data for a second pathogen B.

Once a weight has been assigned to every edge, the system 10 generates aweighted directed graph, describing the probability P that each node Ncan infect another node, as shown in FIG. 6. The system 10 computes theweights on a continuous basis as real-time data streams in from the RTLS12 installation. In some instances, an edge between two nodes mightdisappear (e.g., when the time that the infectious pathogen is outsidethe body exceeds a particular duration, when an infected entity executesa hygiene protocol such as when a nurse is infected through contact withinfected washes hands with hand sanitizer, and so forth).

At 108, a list of nodes 18 with likelihoods of infectious areas can bedisplayed on the display device 26 for viewing by a medicalprofessional. In some examples, the list of nodes include the nodes 18with infection likelihoods that satisfy the infected criterion.

EXAMPLE

The following are two example algorithms, implemented on the electronicprocessor 22, to perform the disclosed operations:

Example 1 (For Contact and Droplet Precautions)

-   -   Nurse N1 enters Room R1 to meet Patient P1 lying on Bed B1.    -   N1 is in charge of taking care of P1    -   P1 is suffering from a currently undetected infectious medical        condition, M1 involving Pathogen PG1.    -   PG1 can only be spread via contact, i.e. not via Droplets or        Airborne transmission.    -   PG has a known lifetime of 5 days outside the body under certain        conditions (e.g. certain temperature, humidity, etc.)    -   N1 wheels out P1 to another department for some tests in a        Wheelchair, W1.    -   System monitors all entities that are either in the same zone or        within 1 m of P1, N1 and W1 and stores location information of        all tagged entities in the hospital on the server.    -   30 minutes after N1 and P1 have left R1, Nurse N2 enters Room        and happens to make physical contact with B1 momentarily and        leaves R1.    -   P1 is not the responsibility of N2.    -   1 day later P1 develops symptoms which correspond to condition        M1.    -   3 days later, N1 and N2 are found to be suffering from symptoms        corresponding to condition M1    -   While it is obvious to the Infection Control Manager, I1 that N1        caught the infection from P1, it is not clear how N2 also caught        the infection.    -   Parameters are entered into the system. System forms directed        graph.    -   Directed graph shows that an edge exists between B1 and N2.    -   Edges also exist which contain B1, P1, N1, W1 and N2    -   All assets sharing edges with B1, P1, N1, W1 and N2 are        disinfected.    -   All persons sharing edges with B1, P1, N1, W1 and N2 are        quarantined and/or prescribed appropriate treatment.

Example 2 (For Airborne Precautions)

-   -   Patient P1 is lying on Bed B1 in Room R1.    -   P1 is suffering from a currently undetected infectious medical        condition, M1 involving Pathogen PG1.    -   PG1 can be spread via Airborne transmission.    -   PG1 has a lifespan of 5 hours outside the body.    -   Nurse N2 enters Room R2 to pick up some supplies 1 hour after P1        has been placed in R1.    -   Rooms R1 and R2 share ventilation    -   Nurse N2 inhales PG1 in R2    -   N2 develops M1 after 24 hours.    -   Parameters are entered into the system. System forms directed        graph.    -   Directed graph shows that an edge exists between P1 and N2 due        to shared ventilation between R1 and R2.    -   P1 is moved to a room with isolated ventilation and N2 is        quarantined.

The disclosure has been described with reference to the preferredembodiments. Modifications and alterations may occur to others uponreading and understanding the preceding detailed description. It isintended that the invention be construed as including all suchmodifications and alterations insofar as they come within the scope ofthe appended claims or the equivalents thereof.

The invention claimed is:
 1. An infectious disease transmission trackingsystem, comprising: a real-time locating system (RTLS) configured totrack locations of tags in a monitored area; at least one electronicprocessor in operative communication with the RTLS to receive locationsof tags in the monitored area; and a non-transitory storage mediumstoring: a map of the monitored area; a nodes database storinginformation on nodes wherein each node is a person, a mobile object, ora map zone and the nodes database stores information on the nodesincluding at least (i) an identification of each node as a person, amobile object, or a map zone, (ii) an identification of a tag associatedwith each node that is identified as a person or a mobile object, (iii)locational information on the map for each node that is identified as amap zone, and (iv) an infection likelihood for each node with respect toa tracked pathogen; a pathogen database storing infectious transmissioninformation for at least the tracked pathogen including one or moretransmission modes for the tracked pathogen and at least one noderesidency time for the tracked pathogen; and instructions readable andexecutable by the at least one electronic processor to perform aninfectious disease transmission tracking method including: computing apathway on the map of at least one infected node using locations of thetag associated with the infected node received from the RTLS wherein aninfected node has a non-zero infection likelihood respective to thetracked pathogen which satisfies an infected criterion; computing aninfectious zone on the map along the pathway using the infectioustransmission information stored in the pathogen database; for each nodecontacting the infectious zone, adjusting the infection likelihood ofthe contacting node in the nodes database based on at least theinfectious transmission information for the tracked pathogen anddesignating the contacting node as an infected node if the updatedinfection likelihood of the contacting node satisfies the infectedcriterion.
 2. The system of claim 1, wherein the at least one electronicprocessor is further programmed to: display, on a display device, a listof nodes with infection likelihoods that satisfy the infected criterion.3. The system of claim 2, wherein the at least one electronic processoris further programmed to: determine, for each node in the list of nodes,a time-dependent value in which the corresponding node is determined tohave an infection likelihood of zero.
 4. The system of claim 3, whereinat least one electronic processor is further programmed to: set thetime-dependent value to zero upon receiving an indication that thecorresponding node is no longer infectious.
 5. The system of claim 1,wherein the RTLS includes one of: (1) radiofrequency identification(RFID) tags and RFID tag readers; or (2) tags including an infrared (IR)receiver and a radiofrequency (RF) transceiver; a monitor configured totransmit IR signals throughout the monitoring area and output IR signalswith unique IDs sensed by the tags, and an RF tracking communicationstation 44), operative to read IR IDs sensed by the tags.
 6. The systemof claim 2, wherein: the RTLS includes monitoring of usage of sanitarystations distributed through the monitored area; the map includeslocations of the sanitary stations monitored by the RTLS; and theadjusting of the infection likelihood of the contacting node in thenodes database is further based on monitored usage of a sanitary stationat contact with the infectious zone.
 7. The system of claim 1, whereinthe adjusting of the infection likelihood of the contacting node in thenodes database is functionally dependent on at least a distance betweenthe infected node and the contacting node and a time passed since theinfected node was in contact with the tracked pathogen.
 8. The system ofclaim 1, wherein the adjusting of the infection likelihood of thecontacting node in the nodes database is functionally dependent on atleast one of a type of surface of the infected node wherein the infectednode is a mobile object or a map zone, a temperature in the vicinity ofthe node; and a humidity value in the vicinity of the node.
 9. Thesystem of claim 1, wherein the adjusting of the infection likelihood ofthe contacting node in the nodes database is functionally dependent onat least an order of node from the node which is considered to be theoriginal source of infection; a number of times that the nodes haveencountered each other since first getting infected; and an execution ofhygiene regime.
 10. The system of claim 7, wherein the adjusting of theinfection likelihood of the contacting node in the nodes database isdetermined by the equation:p=f(d,a,t,s,T,H,o,i,h),  (1) where d is a distance between two nodes; ais air flow characteristics between the two nodes; t is a time passedsince one of the nodes was last in contact with the pathogen ofinterest; s is a type of surface of the node, T is a temperature in thevicinity of the node; H is a humidity value in the vicinity of the node;o is an order of node from the node which is considered to be theoriginal source of infection; I is a number of times that the nodes haveencountered each other since first getting infected; and h is anexecution of hygiene regime.
 11. The infectious disease transmissiontracking system of claim 1, wherein the: real-time locating system(RTLS) including tags and tag readers, wherein the tag readers aredistributed through the monitored area and are configured to tracklocations of the tags in the monitored area; and wherein the adjustingof the infection likelihood of the contacting node in the nodes databaseis determined by the equation:p=f(d,a,t,s,T,H,o,i,h),  (1) where d is a distance between two nodes; ais air flow characteristics between the two nodes; t is a time passedsince one of the nodes was last in contact with the pathogen ofinterest; s is a type of surface of the node, T is a temperature in thevicinity of the node; H is a humidity value in the vicinity of the node;o is an order of node from the node which is considered to be theoriginal source of infection; I is a number of times that the nodes haveencountered each other since first getting infected; and h is anexecution of hygiene regime.
 12. A non-transitory computer-readablestorage medium, comprising: a map database storing a map of a monitoredarea; a nodes database storing information on nodes wherein each node isa person, a mobile object, or a map zone and the nodes database storesinformation on the nodes including at least (i) an identification ofeach node as a person, a mobile object, or a map zone, (ii) anidentification of a tag associated with each node that is identified asa person or a mobile object, (iii) locational information on the map foreach node that is identified as a map zone, and (iv) an infectionlikelihood for each node with respect to a tracked pathogen; a pathogendatabase storing infectious transmission information for at least thetracked pathogen including one or more transmission modes for thetracked pathogen and at least one node residency time for the trackedpathogen; and instructions readable and executable by at least oneelectronic processor to perform an infectious disease transmissiontracking method including: receiving, from one or more tag readers of areal time location system (RTLS), locations of one or more tags of theRTLS in the monitored area; computing a pathway on the map of at leastone infected node using locations of the tag associated with theinfected node received from the RTLS wherein an infected node has anon-zero infection likelihood respective to the tracked pathogen whichsatisfies an infected criterion; computing an infectious zone on the mapalong the pathway using the infectious transmission information storedin the pathogen database; for each node contacting the infectious zone,adjusting the infection likelihood of the contacting node in the nodesdatabase based on at least the infectious transmission information forthe tracked pathogen and designating the contacting node as an infectednode if the updated infection likelihood of the contacting nodesatisfies the infected criterion.
 13. The non-transitorycomputer-readable storage medium of claim 12, wherein the infectiousdisease transmission tracking method further includes: controlling, withthe at least one electronic processor, a display device to display alist of nodes with infection likelihoods that satisfy the infectedcriterion.
 14. The non-transitory computer-readable storage medium ofclaim 13, wherein the infectious disease transmission tracking methodfurther includes: determining, for each node in the list of nodes, atime-dependent value in which the corresponding node is determined tohave an infection likelihood of zero.
 15. The non-transitorycomputer-readable storage medium of claim 13, wherein the infectiousdisease transmission tracking method further includes: adjusting theinfection likelihood of the contacting node in the nodes database basedon monitored usage of a sanitary station in the monitoring area atcontact with the infectious zone.